This invention relates to an electromagnetically operated fixed displacement pump, which comprises an electromagnetically reciprocating member such as a diaphragm plunger and an electromagnet including an electromagnetic coil driving the reciprocating member and an armature and executes a pumping operation according to a preset discharge rate.
This type of pump is known and disclosed in, for instance, in U.S. Pat. No. 4,537,565. The disclosed pump comprises a pump body, a pump head provided at an end thereof in the axial direction and having an inlet port and a discharge port, the pump body accommodating an electromagnetic coil, a movable armature movable in the axial direction of the pump body with energization of the coil and a reciprocating member movable in unison with the armature in the axial direction of the pump body, the pump head having a pump chamber defined therein and communicating with the inlet port and the discharge port via valve means, the volume of the pump chamber being varied with the reciprocation of the reciprocating member to obtain pumping operation, a stroke adjustment assembly disposed on the side of the pump body opposite the pump head in the axial direction of the pump body for adjusting the stroke of the armature, the stroke adjustment assembly including a stop member displaceable in the axial direction of the pump body, a rotary knob constituting an operating means for causing the displacement of the stop member by external manual rotating operation, and coupling means operatively coupling the rotary knob and the stop member, a stroke number control means for adjustably selecting the frequency of energization of the electromagnetic coil to thereby control the stroke member of the armature, the pump body being provided with power source connection means for energizing the electromagnetic coil.
The pump disclosed in the above U.S. Pat. No. 4,537,565 is a commonly termed diaphragm pump employing a diaphragm as a reciprocating member.
U.S. Pat. No. 4,272,225 discloses a commonly termed plunger type pump using a plunger as a reciprocating member.
In either of these electromagnetically operated fixed displacement pumps, it is necessary to adjust the stroke of the reciprocating member in dependence on the kind of the operating fluid supplied to the pump used in various fields and the preset discharge rate. In addition, for the adjustment of the stroke number of the reciprocating member it is necessary to adjust the control number of the electromagnetic coil controlled by pulse signal. To this end, a pump is prepared for each specification, which is determined in accordance with the use, function level, rated power source in the destination, price and so forth. The main specification of these pump products is the preset discharge rate. The discharge rate is set either by a single control, in which only the stroke is controlled, or a complex control, in which both the stroke and the stroke number are controlled.
The control of the stroke is usually made by adjusting the position of the stop member to be struck by the reciprocating member at the stroke end thereof, as shown in both the United States patents noted above. The stroke adjustment assembly to this end is disposed in the rear end position of the stroke of the reciprocating member. If the pump head is in a front end part, the assembly is provided in a rear end part of the pump body.
The stroke number adjustment is based on electric control of the number of pulses supplied to the electromagnetic coil, as shown in the above U.S. Pat. No. 4,537,565. The stroke number adjustment means to this end is accommodated in the pump body. An operating unit for the stroke number adjustment is provided together with a rotary knob for the stroke adjustment noted above on an operating panel which is disposed in a rear part of the pump body.
In the prior art structure, the control unit for setting the discharge rate is fixed with each product in dependence on the specification. Therefore, although the control is made individually in a predetermined range with a particular product specification, it is impossible to cope with a case requiring control beyond the range noted above or cope with differences of other conditions such as rated power source, that is, to this end it is necessary to prepare a pump product of a new specification. Therefore, even when there is no particular need for altering the pump body structure, the product specifications are extremely various to correspond to the individual conditions. Such various product specifications make difficult the cost reduction by mass production and are also inefficient in the product supply management. Particularly, up to date the purposes are diversified, and the internationalization of the destination is promoted more and more. This means that it is necessary to provide products to be able to meet such a great scope of specifications instantly. With the prior art pump products, however, no measure is found in this respect.